A primitive data type refers to a basic data type that is built directly into the language. Unlike objects, primitive types in PHP are not reference types and generally represent simple values.
#1 - boolean
<?php
// The boolean data type stores a binary value, either true or false
$isReady = true;
$isComplete = false;#2 - integer
<?php
// Integer data type represents whole numbers
$decimal = 10;
$negative = -5;
$hexadecimal = 0xa00d; // Hexadecimal starts with 0x
$octal = 0o633; // Octal starts with 0o (PHP 8.1+)
$binary = 0b1010; // Binary starts with 0b#3 - String
<?php
// The string primitive type stores textual data
$x = 'x';
$y = "y";
// Strings can span multiple lines using heredoc or nowdoc syntax
$sentence = <<<EOT
xxx,
yyy
EOT;
// Or with double quotes for variable interpolation
$multiline = "This is a
multi-line string";#4 - float (double)
<?php
// Float data type represents floating-point numbers
$float = 3.14;
$scientific = 1.2e3; // 1200
$negativeFloat = -2.5;#5 - Array
<?php
// Arrays can store multiple values of different types
// Indexed arrays
$stringArray = ['a', 'b'];
$mixedArray = ['a', 1, 'b', 2];
// Associative arrays
$assocArray = [
'name' => 'John',
'age' => 30
];
// Using array() syntax (older style)
$oldStyleArray = array('a', 'b', 'c');
// Multi-dimensional arrays
$multiDim = [
[1, 2, 3],
['a', 'b', 'c']
];#6 - Null
<?php
// null represents a variable with no value
$nullVar = null;#Type checking and conversion
<?php
// Type checking functions
is_string($x); // true
is_int($decimal); // true
is_float($float); // true
is_bool($isReady); // true
is_array($stringArray); // true
is_null($nullVar); // true
// Type conversion
$stringNumber = "123";
$intValue = (int) $stringNumber; // Cast to integer
$floatValue = (float) $stringNumber; // Cast to float
$stringValue = (string) $decimal; // Cast to string
$boolValue = (bool) $decimal; // Cast to boolean
// Strict comparison
$strictCheck = 123 === "123"; // false (different types)